Carbonization process



H. O. LOEBELL El AL Feb. 20, 1934. I

CARBONI ZATION PROCE S S Filed Feb. 14, 1950 2 Sheets-Sheet 2fJ-wvwntozs HENRY O. LOEBELL ALBERT L. KLEES III Patented Feb. "20, 19341,948,472 CARBONIZATION rnocass Henry 0. Loebell, Malba, and AlbertLudwig Klees, Long Beach, N. Y., assignors to Henry L. Doherty, NewYork, N. Y.

Application February 14, 1930. Serial No. 428,297 15 Claims. (01402-26)The invention relates to processes for carbonizing solid carbonaceousmaterials in thin layers,

and more particularly it concerns the carbonization of fuel mixturescontaining bituminous 5 materials in which the fuel mixtures aresubjected to pressure and/ or to a briquetting operation prior to,during or subsequent to the carbonizatlon step.

Various methods are already known for th carbonization of solid fuelmixtures in thin layers.

An example of such a process which makes possible the successfulproduction of high grade smokeless fuel briquets, is disclosed in thecopending application of Henry 0. Loebell for United States, Patent Ser.No. 347,802 filed March 18, 1929.' The invention therein describedprovides for the carbonization of fuel mixtures in thin layers whileholding the. same under determinate pressures.

The necessary carbonization a rotatable idler member.

.The fuel mixture is fed in an even layer upon the endless belt and thelatter is then moved to bring the fuel into engagement with the rotor bymeans of traction between the belt and rotor. .The degree of thepressure developed upon the fuel layer being carbonized is varied bymodifying the tension in the endless, fuel-carrying belt,

While the process and apparatus as described in the aforementionedcopending application yields satisfactory results when utilizing certaintypes of fuel mixtures, it has been found that when other mixtures,-andespecially those containing a large percentage of volatileconstituents,-were processed, there was sometimes a tendency for aporous cell structure to develop in the briquets and for the briquets insome instances to stick slightly in the molds and to fail to dischargeuniformly from the belt. more, dueto the considerable period of timedur- Furtherened crusts to form on the upper surface thereof; and thiscrust would fracture when it came into pressing engagement with therotor, thus giving the finished briquet a roughened appearance.

Sometimes these cracks would appear in the briquets after carbonizationand during the cooling thereof.

It has now been discovered that it is possible to overcome these variousdifficulties in connection with carbonization operations involving aprocess of the type mentioned. Any tendency of the briquetted fuelmixture to stick in the mold after carbonization may be neutralized bycompacting the thin layer of fuel through application of a relativelylow degree of prepressure to it immediately after its distribution uponthe carbonizing belt and before any substantial part of it has beenbrought to a carbonization temperature. Furthermore this sticking may beprevented by preheating the mold or belt to a carbonization range, priorto charging the layer of fuel onto the hot belt. This permits the rapidformation of a surface film of carbonized fuel upon the belt, which filmis weak and brittle, and permits the carbonized briquet later to bereadily discharged from the belt. 1

The undesirable formation of an upper crust on the fuel layer prior tocontact thereof with the rotor is preferably prevented by the employmentof a radiation screen of suitably-reenforced refractory material, sodisposed as to prevent direct radiation of heat from the hot rotor tothe fuel until the latter is closely adjacent the rotor.

While the preforming and compacting of the fuel layer upon the conveyorbelt may be accomplished by either a roller or a flat plate orequivalent device, it is desirable in any event that the device beadapted to give the free surface of the fuel layer the same generalcontour as the cylindrical surface of the rotor. It will thus serve bothto give satisfactory density to the raw fuel-and a correspondingincrease in density to the carbonized briquet,--as well as to so shapethe upper surface of the fuel layer as to substantially minimize anytendency to cracking thereof upon contact thereof with the groovedsurface of the hot rotor. Where the material therefore is compressed bythe preforming device and shaped so that its top surface conforms withthe cylindrical surface of the rotor, the latter is not forced to breakthrough this upper surface of the fuel which may have been caked alreadyto some degree, especially in the absence of a suitable radiationscreen.

In the accompanying drawings showing certain preferred forms ofapparatus adapted to carry out the invention,

Fig. 1 is a vertical section through one form of the earbonizingapparatus taken on the line 1-1. Of Fig. .2; n

Fig. 2 is a vertical section through the carbonizing apparatus takenalong the line 2--2 of Fig. 1;

Fig. 3 is a verticalsection through another modification of theinvention;

Fig. 4 is a view in perspective of the prepressure device andinterassociated parts; and

Fig. 5 is a somewhat diagrammatic view in perspective of the retort,showing the charging and discharging apparatus and associated parts.

Referring to Figs. 1 and 2 of the drawings, 10 designates a closed,refractory-lined retort housing provided with inspection and explosiondoors 12, 12. A hollow rotor 14 of heat-resistant metal or alloy such asHybnickel is disposed within the retort and has sloping side portions 16extending through openings in opposite side walls of the retort. Therotor is rotatably mounted at its respective ends on suitably journalledrollers 17, 17, and journals 20, 20 carried by supports 22, 22. A ringgear 24, secured to one end of the rotor, is driven from a suitablesource of power through an intermeshing worm gear 26.

For sealing the interior of the retort so as to prevent gas leakagetherefrom past the sloping sides of the rotor, each side wall hassecured thereto, adjacent the openings through which the ends of therotor extends, a hollow annulus 28, having fluid inlet and outletconnections and adapted to have a cooling fluid circulated therethrough.Extensions at each end of the side members 16, are shaped to form flatplates 30,

each provided with a plurality of annular grooves 32, 32 therein.Secured to each plate is a collar 34 faced with high temperaturepacking. An annular sealing member 36 has bearing surfaces respectivelyadapted to contact with a surface of the annulus 28 and with the groovedplate 30, and is normally urged into pressing engagement with both by aspring-operated bellcrank 38, as shown. The annular members 28 and 36,with the plate 30 at each side of the rotor forms an annularlubricant-containing receptacle. Suitable packing rings 39 are setwithin the members 28.

A fluid fuel inlet pipe 40, closed at its mid portion, extends axiallyof the rotor and has both ends connected with a source or sources offuel gas. Concentric therewith is a second pipe 42 adapted toaccommodate a flowing stream of cooling fluid such as water. A layer ofrefractory material 44 enclosed in a heat resistant metal casingsurrounds the pipes 40, 42, as shown. A plurality of fuel nozzles 46directed in a general downward direction are provided within the rotor.The interior of the rotor is in communication with a pair of flues 43,48 through the annular passageways 50, 50 surrounding the respectiveends of the rotor.

A flexible endless conveyor belt of heat-resistant metal or alloy 60,such as those described in the aforementioned copending application ofHenry 0. Loebell, Ser. No. 347,802, is adapted to surround the rotor 14and also to pass around an idler roller 62, disposed within the retort10 with its axis parallel to that of the rotor. ,The exterior surface ofthe rotor and the rotor-contacting surface of the belt 60 may be smoothas shown in Figs. 1 and 2, or they may be suitably designed in themanner disclosed in my aforementioned copending application forcooperating to produce carbonized fuel in briquet form as shown heremore particularly in Fig. 4. The interior of the idler 62 may if desiredbe heated. This may be accomplished in the same manner as the rotor isheated, or it may be .done in other gases being withdrawn through theflue 72. A

transverse pipe 73 disposed below the rotor is provided with a pluralityof fan-shaped outlet nozzles 75, and has its ends in communication witha source of hot flue gases such as those produced in the rotor or in theheating chamber 64. Thus a steady flow of these gases over the radiantwindow 66 is accomplished which serves to keep the latter free fromcarbon and the like which might interfere with radiant heat transfer,and which serves also to remove from this zone the carbonization vaporsas rapidly as they issue through the belt and before they can be crackedor otherwise injured by contact with the highly-heated radiant window.Nitrogen or other neutral gases or other slightly oxidizing gases may besubstituted for the flue gases.

For providing the desired degree of tension in the belt 60 duringoperation, and to secure a suitable change in direction thereof as itleaves the rotor, a plurality of weighted rolls 76, 76 are mounted inswingable frame members 78 supported on a cross member 79, which isadapted for vertical sliding movement in slotted end members 80, 80, onthe inside of the retort walls.

For conveying fuel to be carbonized to the belt 60. and for removing thecarbonized fuel from the retort, a transverse endless scraping conveyor90, driven from a suitable power source, is provided, the same havingupper and lower runs and comprising a plurality of cross members orscrapers 92 secured in spaced-apart relation by link members 94 movingalong track Ways inthe refractory side walls 96, 96 at the respectivesides of the conveyor. The upper reach of the conveyor travels in agrooved trough 98.

Solid fuel passes from the hopper 100 through 125 the sealing andmeasuring valve 102 onto the lower reach of the conveyor 90. Any surplusfuel not deposited on the belt 60 during the movement of the conveyor 90across the same, is discharged by the feed conveyor through a gastightseal valve 104 and may be returned to the hopper 100 or conveyedelsewhere. The carbonized fuel deposited upon the upper reach of theconveyor upon the separation of the carbonizing belt and rotor, isdischarged from the retort through the seal valve 106 to a closedconveyor leading to a suitable quenching vessel or to an annealing oven(not shown).

A radiation screen 110 of refractory material, preferably having aportion thereof of heat resistant metal, which may if desired be cooledby the flow of a suitable fluid therethrough,is disposed between thecharging conveyor and the rotor 14, for the purpose of preventingtransmission of radiant heat to the upper surface of the fuel layeruntil the latter is substantially in contact with the hot rotor.

For applying a controlled degree of prepressure to the thin layer offuel prior to contact thereof with the hot rotor, for shaping the topsurface 15 of the fuel layer to conform with that normally imparted toit later by the rotor, and for compacting the fuel charge before it hasbeen subjected to substantial surface heating,-a press-, ing member 116is provided. This may be a roller or a flat plate or equivalent device,but in the form shown this member consists of one or more rollersmounted on a'rotatable shaft 118 for limited sliding movement thereonand for rotation therewith. Each rollers may have its curved surfacefluted. grooved or otherwise shaped to correspond to the surface shapeof the rotor. a suitable driving connection with the rotor or with anindependent source of power, in such manner that the outer surface ofthe rollers 116 and the carbonizing belt 60 move at substantially thesame speed.

The respective ends of the shaft 118 are resiliently urged downward bysuitable means such as the tension springs 120 in a manner to yieldinglypress the rollers 116 with a predetermined pressure against thecarbonizing belt and the fuel carried thereby. Any well-known means maybe employed for adjusting the degree of the downward pressure exertedupon the shaft and rollers by the springs l20,-to vary the amount ofpressure applied to the fuel on the belt.

For adjusting the thickness of the layer of fuel to be deposited uponthe carbonizing belt by the conveyor 90, a vertically-adjustable,supporting member 130 is disposed within the retort below the belt 60and rollers 116. and in contact with the former. A series of rollers aremounted as shown in the upper surface of the member 130 to reducefriction between the belt 60 and member 130.

A vapor and coal gas outlet 132 leads from the upper part of the retortto the'usual scrubbers and condensers.

According to the modification shown in Fig. 3, tlie fuel mixture to becarbonized is deposited by the lower reach of the conveyor 90 into anelongated hopper 140 from which it is fed continuously through thesealing and measuring valve 142 and then quickly falls by gravity uponthe carbonizing belt 60 at approximately the point of juncture of thelatter with the hot rotor, as

shown. A roll or the like 144, driven at about the same speed as thebelt 60, maintains a uniform point of contact of the rotor and the belt,and serves to compact the fuel as it contacts with the rotor. Atroughlike member 91 cooperates with the belt 60 to convey thecarbonized fuel or briquets from the rotor to the upper reach ofconveyor 90. In this modification, the elapsed time between the feedingof the fuel to the belt and the passing thereof into pressing contactwith the .hot rotor is so short that the radiation screen and. theprepressure member, such as shown in Fig. 1, are not necessary. Aheating chamber 64, provided with a radiant window or heat-trans ferringsurface 66, is also provided. Conduit 146 conveys the carbonizationvapors from the retort; and conduit 148 conducts away flue gases fromthe chamber 64. The rotor is heated and otherwise served in the samemanner as described in connection with the modification shown in Figs. 1and 2. The, refractory side wall 96 of thehousing forthe fuel feedingdevice adjacent the carbonizing belt is out back sufficiently to permitready escape past this point of the carbonization vapors and gases firstformed at the point of contact of the fuel with thehighly heated vtionheat in-the process.

The shaft is adapted to be rotated by rotor and before they have beensubstantially cracked or otherwise injured by heat flowing fromthe'rotor.

' The vapors and coal gas formed in the retort during the carbonizationof relatively high volatile coals and fuel mixtures are subjected to theusual scrubbing and condensing operations and may then be takentostorage, or they maybe burned for supplying the necessary carboniza- Incertain instances the carbonization' vapors within the retort may bediluted with hot flue gases such as those produced by the combustionwithin the rotor for reducing the plastic properties of the fuel, andassisting in the carbonization. Air or other oxygen-containing gas maybe introduced into the carbonizing chamber with or without flue gasesfor supplying additional heat directly to the fuel mixture beingprocessed.

In a type of operation where the mixture carbonized consists of anywherefrom 25 to 50% of through the machine and the final mixture of fluegases, and carbonization vapors leaving the carbonizing furnace will besufficiently combustible so that this hot mixture can be used to providethe heat for the carbonization process. In such a case, low grade coalscan be carbonized to form a high grade product; and no condensing,scrubbing or auxiliary equipment is necessary, because the carbonizationgases made are directly returned to the machine to provide the heatnecessary for carbonization. The flue gases have a slight oxidizingeffect tending to destroy the plastic nature of the fuel mixture, thusassisting to retard any tendency of the mixture to stick in the cells ofthe carbonizing belt. This sticking tendency may also be retarded bypreheating the carbonizing belt prior to introducing the fuel mixtureupon it, as for example by heat applied thereto as it passes around theheated idler roll. (See Fig. 1.) Other means for applying heat to thebelt previous to the placing of the fuel charge thereon may besubstituted for the indirect heating thereof through the idler roll, aswill be apparent to those skilled in the art.

Very satisfactory smokeless fuel briquets have been prepared byprocessing in accordance with the present invention a fuel mixturecontaining 80% anthracite culm and 20% Skelly pitch, (a petroleum pitchhaving a melting point around 275 F.,) all ground to less than 20 mesh.This fuel mixture was preheated in a fluxing vessel to 625 F., and wascharged hot in a thin layer the neighborhood of 1385 F. and wascarbonized over a period of 10 minutes by this heat applied to both thetop and bottom surfaces of the layer, following which the briquets weredischarged and quenched.

Similar results were obtained by processing a fuel mixture containing50% of a petroleum coke (produced bythe pressure distillation ofpetroleum oil), which had been given a preheating treatment to 1400 F.30% of the same petroleum coke untreated, and 20% of Skelly pitch, allground to less than 10 mesh. After preheating the mixture to 640 F., itwas charged in a thin layer 1% inches in thickness on the briquettingbelt. This fuel layer was then passed under the prepressure andpreforming roller where it was reduced to 1%; inches in thickness undera pressure of 10 pounds per sq. in. The preformed fuel layer was thenpassed into contact with two highly heated surfaces maintained ataverage temperatures of 1425 F. for 10 minutes while under a lowpressure of lb. per square in.- The pre-, pressed fuel layer wassubjected to 1 minute preheat radiated thereto from the rotor prior tocontacting therewith. Prepressures of between 1 pound to 100 pounds persq. in. on the raw fuel mixture may be employed with good results. For

degree of compression pressure free from substantial unregulatedvariations due to volume changes occurring in the fuel during suchcarbonization.

3. The process of carbonizing solid fuel which comprises, compacting'andshapingunder pressure a thin layer of finely divided solid carbonizablefuel while preventing substantial carbonization of the fuel, thereaftermoving the compacted and shaped fuel layer along a curved path in acarbonization zone while carbonizing it by heat applied to at least oneside of the layer during such movement, continuously exerting a lowregulated pressure upon the fuel layer being carbonized in a directiontransversely of the free surface of the latter irrespective of volumechanges occurring in the fuel during such carbonization,

instance, prepressures of 25 pounds per sq. inch preventing substantialchange in the surface are suitable when briquetting and carbonizingDubbs pressure still residues, whereas to 100 pounds per sq. inch may beused in high volatile coals under like conditions.

The modification of the invention shown in Fig. 3 is especially adaptedfor processing flowing preheated fuel mixtures which are near thecarbonization temperature as they enter the retort. The use of preheatedfuel is preferable though not essential, and cold fuel mixtures havebeen satisfactorily carbonized according to the invention. carbonizationtemperatures of from 900 F. to 1800 F. have been used; and goodsmokeless fuel briquets have been produced in as short a time as threeminutes exposure to heat from the rotor.

A wide variety of carbonaceous fuels and fuel mixtures may be processedsatisfactorily in accordance with the invention. For example, ores formetallurgical purposes may be briquetted with carbonaceous materials.The use of prepressure is particularly advantageous where fuel mixturesof relatively-high volatile content and of comparatively low density arebeing processed. The

' resultant briquets possess dense structure, and

the external surfaces thereof are relatively free from cracks such asare sometimes caused by shrinkage of an uncompacted mass duringcarbonization or by the action of the rotor in breaking through apartially-carbonized upper surface of fuel which covers underlyinglayers of loose, uncompacted fuel.

The invention is susceptible of modification within the scope of theappended claims.

We claim:

1. The process of carbonizing solid fuel which comprises, compacting andreshaping the opposite surfaces of a uniform thin layer of finelydivided solid carbonizable fuel while the same is below itscarbonization temperature, thereafter carbonizing the compacted andreshaped fuel while preventing substantial disturbance of the individualfuel particles and while continuously maintaining a regulated lowpressure upon the said fuel, applied thereto in a direction so as tointersect the surfaces thereof.

2. The process of carbonizing solid fuel which comprises, compacting andreshaping to a selected conformation under pressure a thin layer offinely divided solid carbonizable fuel while preheating the same butwhile preventing substantial carbonization of the fuel, continuouslymoving the compacted and reshaping fuel layer through a carbonizationzone while carbonizing it by heat applied to two opposite surfaces ofthe layer during such movement and while continuously subjecting thefuel layer being carbonized to a low shape of the fuel layer duringcarbonization, and at a point in the said path releasing the pressureand reversing the curvature of the said path for discharging thecarbonized fuel from the carbonization zone.

4. The process of carbonizing solid fuel which comprises preheating abody of finely-divided solid fuel to a temperature below itscarbonization temperature, thereafter disposing the hot fuel in auniform thin layer having a free surface, compacting the fuel layer andshaping the free surface thereof to a selected configuration, thenmoving the compacted and shaped fuel into and through a carbonizationzone, and carbonizing the fuel while continuously exerting a regulatedlow pressure upon the fuel layer and while preventing both substantialchange in the surface shape of the layer and substantial disturbance ofthe individual fuel particles during the carbonization, and thereafterconcurrently removing the carbonized fuel from the carbonizing zone andreleasing the said pressure.

5. The process of carbonizing solid fuel which comprises disposing solidcarbonizable material in a regulated uniform thin layer having a freesurface, compacting under pressure the fuel in the said layer whileheating the same to temperatures below the carbonization temperaturethereof, moving the compacted fuel into a carbonization zone andcarbonizing the said fuel layer under low pressure,. and maintaining thesaid pressure upon the fuel layer substantially throughout thecarbonization independently of any volume changes occurring thereinduring such carbonization.

6. The process of carbonizing solid carbonizable fuel which comprisesdisposing a fuel mixture in a uniform thin layer of regulated thicknesshaving a free surface, compacting the said fuel layer while shaping thefree surface thereof to a selected configuration, carbonizing thecompacted and shaped fuel layer while continuously maintaining thelatter under a low pressure maintained substantially throughout the saidcarbonization, and shielding the thin fuel layer from carbonizing heatuntil the.layer is about to be subjected to the said pressure.

7. The process of carbonizing solid carbonizable fuel which comprisesforming a thin uniform layer of the said fuel having a free surface andconcurrently moving the said layer to a carbon ization zone, compactingthe said fuel layer and providing the same with a selected surfaceconformation prior to the beginning of carbonization thereof, thereafterconcurrently carbonizing the thin fuel layer while continuouslymaintaining the same under a low regulated compresa temperature belowthe low temperature carbonization range, quickly compacting the saidfuel layer while shaping both the said free surface of the layer and theopposite surface thereto to form selected configurations correspondingto the opposite surfaces of the briquette to be formed, carbonizing thesaid thin layer while continuously maintaining thereon a regulatedlowdegree of pressure independently of volume changes in the layer duringthe carbonization and while preventing substantial disturbance of theindividual fuel particles during the carbonization, and shielding thepreheated fuel layer from carbonizing heat until shortly before thelatter is subjected to the last-named pressure.

10. The carbonization process which comprises preheating solidbituminous fuel to a temperature near but below its carbonizationtemperature, disposing the preheated fuel in a thin unconfined layerhaving a free surface, quickly compactirig the said fuel layer under apressure of from 1 to 100 pounds pe'rsquare inch while concurrentlyshaping the free surface of the fuel layer to'a selected configuration,thereafter moving the compacted and-shaped'fuel layer into acarbonization zone thereby carbonizing the same, continuouslymaintaining the fuel layer under a low regulated pressure maintainedthroughout the carbonization substantially independent of volume changesoccurring in the layer while preventing substantial disturbance in thearrangement of the individual fuel particles until the carbonization issubstantially completed, and thereafter concurrently releasing thepressure and removing the carbonized fuel from the carbonization zone.

11. The process of carbonizing solid fuel which comprises disposingfinely divided solid carbonizable fuel in a thin layer having a freesurface, compacting and shaping to a selected configuration underpressure a surface of the fuel layer while the fuel'is at temperaturesbelow the carbonization temperature, moving the compacted and shapedfuel into and through a carbonization zone thereby carbonizing the fuelwhile continuously exertinga regulated low compression pressure upon thefuel throughout the said carbonization applied transversely of the freesurface thereof, and preventing substantial change in the surfaceconfiguration of the fuel layer during the said carbonization.

12. The process for the production of carbonized fuel briquettes whichcomprises, preheating a finely divided mixture of petroleum coke andpitch to a temperature near but below its carbonization temperature,continuously forming the preheated mixture in a thin uniform layerhaving a free surface, compacting the layer under a pressure of from 1to pounds per square inch prior to substantial carbonization, formingthe same into a plurality of separate portions while reshaping the freesurface of the layer to a selected configuration, moving the thuscompacted and shaped fuel into and through a;high temperatureheat-radiating-and-conducting zone thereby carbonizing the said fuel,maintaining a low regulated pressure upon the layer of fuel and appliedin a direction intersecting the free surface thereof substantiallythroughout the said carbonization, gradually increasing the saidpressure during at least the early stages of the carbonization, andconcurrently releasing the said pressure and removing the carbonizedbri- 100 quettes from the carbonizing zone...

13. The carbonization process which comprises carbonizing solidbituminous fuel in a thin uniform layer having a free surface whilemoving the thin layer en masse along a curved path without substantialdisturbance of the individual fuel particles during the saidcarbonization, and continuously applying a regulated low compressionpressure transversely upon the said free surface of the fuel layersubstantially throughout the carbonization.

14. The process of carbonizing bituminous fuel which comprises forming athin uniform layer of the said fuel having a free surface, subdividingthe said layer into a plurality of shallow portions, passing the saidportions so subdivided in succession through a carbonizing zone therebycarbonizing the portions, and exerting a regulated low compressionpressure transversely upon the free surface of the said fuel portionssubstantially throughout the carbonization.

15. The process of producing carbonized fuel briquettes, which comprisescontinuously carbonizing finely divided solid bituminous fuel while thelatter is divided into a plurality of thin briquette-shaped portionseach having a free surface, continuously applying a low regulatedpressure transversely upon the free surface of the said portionssubstantially throughout the carbonization independently of volumechanges occurring in the fuel portions during such carbonization, andsubsequently releasing the said pressure and continuously discharging inbri- .quette form the thus carbonized fuel.

/ ALBERT LUDWIG KLEES.

HENRY O. LOEBELL.

